The Oreja software package (available from www.liv.ac.uk/psychology/Downloads/Oreja.htm) was designed to study speech intelligibility. It is a tool that allows manipulation of speech signals to facilitate study of human speech perception. A feature of this package is that it uses a high-level interpreted scripting environment (MATLAB), allowing the user to load, break down into different channels, analyze, and select the parts of the signal(s) of interest (e.g., attenuation of the amplitude of the selected channels, addition of noise, etc.).